Wash the red potatoes thoroughly and cut them into evenly sized quarters. Place them in a large pot and cover with cold water. Add a pinch of salt and bring to a boil, then simmer for about 10-15 minutes until fork-tender.

Drain the potatoes and prepare an ice bath. Plunge the warm potatoes into the ice bath for about 5 minutes.

Steam the eggs for 15 minutes. Transfer to the ice bath for another 5 minutes.

In a medium bowl, combine the mayonnaise, sour cream, and Dijon mustard. Whisk until smooth.

Chop the cooled potatoes and peeled eggs into small pieces.

In a large mixing bowl, combine the diced potatoes, chopped eggs, celery, red onion, dill, and chives. Toss gently.

Pour the dressing over the salad ingredients and gently fold together.

Season with additional salt and pepper as desired. Chill in the refrigerator for at least 30 minutes before serving.